<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
		<title></title>
		<style type="text/css">
			*{
				padding: 0;
				margin: 0;
			}
			.aaa{
				width: 100%;
				height: 100px;
				background: #ededed;
				position: relative;
			}
			p{
				background: red;
				position: absolute;
				bottom: 0;
				width: 100%;
			}
		</style>
	</head>
	<body>
		<div class="aaa">
			111
			<p class="btn">2222</p>
		</div>
	</body>
</html>
<script type="text/javascript">
	let btn = document.querySelector('.btn')
	let aaa = document.querySelector('.aaa')
	btn.ontouchstart = function(){
		console.log(this);
	}
	
	btn.ontouchmove = function(e){
		console.log(e.targetTouches[0].pageY);
		aaa.style.height = e.targetTouches[0].pageY + 'px'
	}
	
	btn.ontouchend = function(){
		console.log(this);
	}
</script>  